In a battle of two of the biggest hitters in the women's game, Sabalenka seized the initiative after dropping the opening set to win 4-6 6-3 6-4 on Rod Laver Arena.
A year ago, Sabalenka exited the tournament in the fourth round having served 56 double faults, and the 24-year-old's success comes after she remodelled her service action and learned to embrace a calmer mindset.
"I think it's even more enjoyable, I would say, after all those tough matches," said Sabalenka, who had lost three times in slam semi-finals before making the breakthrough here.
"I really feel right now that I needed those tough losses to kind of understand myself a little bit better. It was like a preparation for me.
"I actually feel happy that I lost those matches, so right now I can be a different player and just a different Aryna."
Sabalenka went into the match having won all 20 sets she had played in 2023 but this was a battle she had to win the hard way, maintaining control amid an ultra aggressive approach that eventually broke down Rybakina.
The Moscow-born Kazakh fought all the way and Sabalenka needed four match points to claim a tense final game, with her serve holding up to the finish line despite a double fault on her first chance to clinch it.
"The last game, of course I was a little bit nervous," she said. "I kept telling myself, 'Nobody tells you that it's going to be easy, you just have to work for it, work for it until the last point'.
"That was a tough game. I'm super happy that I was able to handle all those emotions and win this one."
While Sabalenka's name was quickly engraved on the Daphne Akhurst Memorial Cup that was handed to her by Billie Jean King, a blank space was left where the winner's nationality would normally be.
The Belarusian becomes tennis' first grand slam singles champion playing under a neutral flag.
The policy remains controversial, with Russian and Belarusian athletes banned from competing in some other sports, and Sabalenka does not feel it changes much, saying: "I think everyone still knows that I'm a Belarusian player."
Asked if her achievement would be celebrated in her homeland, she added: "I think so. I think people are proud of me."
Sabalenka would be one of the favourites for the Wimbledon title if she is allowed to play, and her success here will be another element for organisers to consider as they decide whether to maintain their ban.
There were a disappointing number of empty seats on Laver for the match, a far cry from 12 months ago, when Ashleigh Barty gave Australia a long-awaited home champion.
One of the biggest cheers of the night was for the 26-year-old as she carried the trophy onto court prior to the start of the match.
It was Rybakina who made the better start, breaking serve to lead 2-1, and, although Sabalenka found her range on return to get back to 4-4, she played her worst game of the match to drop serve again immediately.
The start of the second saw the fifth seed, who will climb to world number two on Monday, up her level, comprehensively outhitting Rybakina in the winner count - she ended up with 51, including 17 aces.
But the errors that might once have accompanied such an approach did not come as Sabalenka kept her nerve in what she described as the best performance of her life.
"I think it's really the best match," she said. "She played unbelievable tennis. I fought so hard to win this one. I think the tennis was great. I'm really happy that it wasn't an easy match. I really enjoyed this battle."
Rybakina had hoped to achieve the rare recent feat in the women's game of holding more than one grand slam title and, although she did not ultimately end up with the trophy she coveted, the 23-year-old demonstrated that she is likely to be a factor at major tournaments for years to come.
"Of course, not the result I wanted today," she said. "But I think overall it was a really good two weeks for me. A really tough match today. So it's just motivation for the next tournaments.
"I think Aryna raised her level in the second set. She played really well, aggressive, less mistakes. I should have been also more aggressive in some moments.
"I had some chances, for sure, to turn it around. But she played really well today. She was strong mentally and physically."